1. Field of the Invention
The present invention relates to a semiconductor device for exchanging data by wireless communication. In particular, the present invention relates to a semiconductor device for exchanging data by wireless communication with the use of an electromagnetic induction method.
It is to be noted that, in this specification, a semiconductor device refers to a device in general which can function by utilizing a semiconductor characteristic, and an electrooptic device, a semiconductor circuit, and an electronic appliance are all included in the semiconductor device.
2. Description of the Related Art
In recent years, an individual identification technology using a semiconductor device for exchanging data by wireless communication has attracted attention. The individual identification technology using the semiconductor device has started to be useful for production, management, or the like of an individual object and has started to be applied to personal authentication. Such a semiconductor device is also referred to as an RFID (Radio Frequency Identification) tag, an IC (Integrated Circuit) tag, an IC chip, an RF tag, a wireless tag, and an electronic tag.
A semiconductor device for exchanging data by an electromagnetic induction method (see Patent Document 1: Japanese Published Patent Application No. H11-11058) will be explained with reference to FIG. 10. A semiconductor device 301 has a coiled antenna portion 302 and a semiconductor circuit portion 303. A terminal 304 of the semiconductor circuit portion 303 is electrically connected to one end 305 of the coiled antenna portion 302. A terminal 306 of the semiconductor circuit portion 303 is electrically connected to the other end 307 of the coiled antenna portion 302.
When a reader/writer including the coiled antenna portion is brought close to the semiconductor device 301, an alternating magnetic field is generated from the coiled antenna portion included in the reader/writer. The alternating magnetic field penetrates the coiled antenna portion 302 in the semiconductor device 301, and an electromotive force is generated between the terminals (one end 305 and the other end 307) of the coiled antenna portion 302 in the semiconductor device 301 due to electromagnetic induction. The semiconductor circuit portion 303 in the semiconductor device 301 is operated by the electromotive force generated due to the electromagnetic induction.